This invention relates to control and regulation devices for hydraulic motors of diverse machinery for use in mechanical handling machinery and equipment, load handling devices (manipulators), or other similar items.
Diverse ways of controlling the load manipulators can be analyzed using as examples, control over loading manipulators intended to obey and execute the operator's commands.
At the present time, load manipulators featuring individual control of the drives are commonly used, wherein each of the drives (hydraulic motors) has a control lever of its own.
However, in the prior art, independently controlled load manipulators are materially disadvantageous in that the operator must effect control over individual operative units (such as the boom or pillar of a load-lifting crane) in succession, and but in extremely rare cases can he control two drives at a time.
The number of control levers in some machines are as large as ten and requires a high level of professional skill on the part of the operator and thus becomes a hindrance to an intense and continuous technological process. Control over such load manipulators gets much more difficult and complicated in cases where they have to operate indoors or in enclosed compartments, where working speed of the manipulator (the operative units) must be limited for the sake of safety operation.
In order to attain higher productive efficiency of the manipulator, use is made of a tracer control method, wherein the control mechanism is similar to the actuating or slave mechanism both geometrically and kinematically. However, inherent in the slave-type manipulators are the following disadvantages: the control mechanism lever must be shifted over a rather long distance; a low accuracy of load positioning is present with a large tracing scale; the operator's hand becomes irritated.
The above disadvantages of the slave-type manipulators can be obviated in the case of the floating (or noncorresponding) control, whereby the manipulator operating member adjusts the traversing speeds of the elements of the operative units proportionate with the travelling of the control mechanism elements. This method is capable of high-accuracy and control over the macromotions of the manipulator operating member by virtue of micromotions performed by the control mechanism elements and hence by the operator's hand, whereby physical effort applied by the latter is much reduced.
The floating-control manipulators, however, suffer from an oversophisticated control design and a lag of control signal, which signal passes through three control circuits, viz., setting member (rectilinear manipulator) - analogue-control mechanism - actuating (or slaving) mechanism.
To simplify control of industrial loading manipulators use is made of a cable drive of control signals to the servo actuator so that the signal from the control device and the feedback signal responding to each setting coordinate are transmitted to servospools of the hydraulic actuator through a cable drive. This arrangement is low in cost and involves no complicated or critically short elements and is operable practically under any type of working conditions.
However, the cable drive control system suffers from the disadvantages that, simultaneous control over different manipulator members is not possible until use is made of an improved design in the slave manipulators, where the feel of the operator's touch need be light. On the other hand, an integrated control over a few members or spool valves and hydraulic motors in different combinations from the same control member (level) is left beyond practical realization due to a sophisticated and cumbersome system of kinematic linking of cables, sheaves and control spool valves with the control lever.
Heretofore known control devices of a boring winch (cf., e.g., USSR Inventor's Certificate No. 176,377 and which are somewhat similar in construction to the present invention were built with articulated rods or links adapted to cooperate with a two-way control valve for the slow- and rapid-run coupling.
Some diverse control devices for hydraulic operative units are now in common use. Thus, for instance, the control lever (cf., e.g., USSR Inventor's Certificate No. 289,051 class B66C 13/18 of 1971) of an excavator or crane mechanism is known to comprise a lever and a rocker arm, both interacting with the control system spool valves. Such structure is somewhat similar to U.S. Pat. No. 3,605,814. For the sake of better operating conditions of the excavator or crane, as for opening the bucket bottom or manipulating the crane winch, the structure employs a microswitch built into the control lever.
Also known is a control system (cf., e.g., French Patent No. 2,271,479 class F15b 13/02) having a directional control valve for hydraulic power units having a control lever, which can be manually shifted to any of the four positions, of which two are indexed ones, and the lever is self-returned into the initial position from the two other positions.
The devices and systems discussed hereinbefore fail to adequately consider operation in, mechanical handling and erecting machinery and equipment, or manipulators provided with three hydraulic motors (with reversal) for rectilinear motion along the three coordinates, i.e., horizontal, vertical and swivel motions controlled by the operator, nor can they provide or reproduce a great diversity of motions which a human hand is able to perform.
The above said disadvantages are partly compensated for in hydraulic directional control valves employed at present in domestic road vehicle machines. Heretofore known hydraulic directional control valves are in fact devices for control and regulation of a few, in particular, of three hydraulic motors at a time, and are adapted for directional control (distribution) of the flow of power fluid in the hydraulic systems of tractors, road vehicles and some other machinery.
The directional control valve incorporates three spools which are kinematically independent of one another. Each of these controls an individual hydraulic motor of its own. All the three control spools are enclosed in a common housing and arranged in parallel to one another. Each of the spools has its own lever with a control knob, the lever being articulately interconnected with the spool. The levers make up an angle with axis of the spools and they swivel on a shaft in the housing and are provided with articulated joints made as spherical rings, each of which is adapted to interact with an individual spool. Through a rotational shaft in their middle portion, the levers are connected to the housing. The valve spools have three main positions, i.e., neutral (or crossover), lifting, and lowering.
The valve spools are of the closed crossover type. When in the neutral position, the valve spools are spring-balanced, the working fluid being admitted but not passed into the hydraulic cylinder chambers. The corresponding control knobs are provided for lifting, lowering and intermediate regulation. A substantial disadvantage of such a directional control valve resides in the fact that three control knobs are to be used to control the three respective actuators. It is thus practically impossible for one operator to shift three control knobs in parallel at a time with an adequate accuracy, which complicates the control process and adversely affects the speed of shifting.
One of the most important practical findings of ergonomics for manually operated controls is that whenever accurate and speedy control is required, it is best to utilize a control member actuated by one hand for rapid traversing and changing over any mechanisms.
The shifting of the control knobs in the aforesaid directional control valve, fails to coincide with the direction of motion of the operative units, in particular, with that of the crane boom luffing and its slewing round the crane pillar.
Such a concordance of movements is especially indispensable when control over a load handling machinery in enclosed compartments or premises, is required and where the location of the load to be handled changes both during gripping the load and when positioning the latter.